Senator Hillary Rodham Clinton answered skeptics Tuesday night by issuing a ringing call for her supporters to rally behind Sen. Barack Obama, saying Democrats cannot afford to stay home in November and let another Republican administration ruin the economy.

“Barack Obama is my candidate,” Clinton said in the final speech of the second night of the convention that will nominate Obama for president.

“No way, no how, no McCain,” she declared in a speech that both blasted the presumed Republican nominee, Sen. John McCain of Arizona, and put forth Obama, her colleague from Illinois, as the man “who must be our president.”

Much of the speculation leading into the Democratic National Convention had centered on how firmly Clinton, the junior senator from New York, would go to bat for Obama, who narrowly edged her for the Democratic nomination in an extraordinarily contentious primary season.

Fire marshals closed the convention floor, which was packed to capacity with Clinton supporters who cheered long and loudly for their candidate. Clinton reserved special gratitude for them and the 18 million other voters who backed her in her primary campaign against Obama.

“To my supporters, my champions — my sisterhood of the traveling pantsuits — from the bottom of my heart: Thank you. Thank you,” she said. “You never gave in. You never gave up. And together we made history.”

But she told those supporters that it was time to take all of their energy and enthusiasm and channel it into electing Obama.

“My friends, it is time to take back the country we love,” she said. “Whether you voted for me or voted for Barack, the time is now to unite as a single party with a single purpose.

“We are on the same team, and none of us can sit on the sidelines,” she added. “This is a fight for the future. And it’s a fight we must win.”

The McCain campaign responded immediately, saying in a statement that “nowhere tonight did [Clinton] say that Barack Obama is ready to lead. Millions of Hillary Clinton supporters and millions of Americans remain concerned about whether Barack Obama is ready to be president.”